I can't reproduce the problem on a test machine (SMP) with eth0 (e100) and eth2 (e1000) Doesn't seem to hang either with commands or custom program. [root@dev4-009 root]# vconfig add eth2 1 Added VLAN with VID == 1 to IF -:eth2:- WARNING: VLAN 1 does not work with many switches, consider another number if you have problems. [root@dev4-009 root]# ifconfig eth2:1 eth2:1 Link encap:Ethernet HWaddr 00:03:47:9A:33:D5 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Memory:fa420000-fa440000 [root@dev4-009 root]# mii-tool eth2:1 SIOCGMIIPHY on 'eth2:1' failed: Operation not supported This is what we would expect since e1000 doesn't support MII ioctl when running in 1000Gbit mode. [root@dev4-009 root]# vconfig add eth0 11 Added VLAN with VID == 11 to IF -:eth0:- [root@dev4-009 root]# mii-tool eth0:11 eth0:11: negotiated 100baseTx-FD, link ok The e100 link works, and also eth1 (e1000 in 100mbit mode). If someone can reproduce the problem, please tell me how and/or do it on a console; it is probably a OOPs.